Hi,
We just recieved an LS1 out of an 04 GTO with a t56 transmission. Its going in a 77 vette. I do have some questions though, it looks as if the engine has been into before. We took the backing plate off of the rear of the engine where the rear main seal is and discovered that it has a comp cam in it.
Here are the specs to it:
http://www.compcams.com/Cam_Specs/Ca...csid=1090&sb=2

One other thing that we found interesting is that it looks as if it has an ARP crank bolt. Why would it have this? The underdrive pulley looks oem and the heads have a casting number of 241.

So I guess we are trying to figure out what the motor really has. Any info on how that cam will do would be great also.

Thanks everyone.

 

That is a pretty mild cam for these motors. Im sure that it runs pretty good but you could def get a bit more out of it with a better cam

 

Probably because they removed the crank pulley to access the cam. A lotta guys replace the bolt for fear it has/will have stretched.

 

The 241 heads are stock casting heads that came in the 04 GTOs, the ARP crank Bolt is also a norm when taking the crank pulley out to do a cam swap, I would also check the springs, retainers and valves. Just to be safe IMO. Other wise you have a very close to stock LS1 in your hands.

Now many people do take heads off when performing a cam swap on LS1. I would check, springs, retainers, and take a look at the valves to make sure they are not beat up. Since it was not your engine I would do a very good once over with heads off. Also do a compression test just to make sure that everything is working well and you don't have a hurt cylinder. Other than that enjoy and have fun with it.

 

Alright thanks everybody.
I didn't figure it was too built, but its still a good foundation. I think it also has the same throttle body because I measured the butterfly valve at 75mm. It has msd plug wires and some autolite sparkplugs that look like they are in good shape.
We might take the heads off, or at least the valve covers.